In general, fat products subjected to prolonged heating at temperatures above 120.degree. C. deteriorate, in that they develop unpleasant aromas and/or smoke.
Although, generally speaking, both odour and taste are meant by "aroma", in this description the emphasis lies on the odour impression which the fat products according to the present invention cause on use. However, the observations made below with respect to the odour also apply to a greater or lesser extent to the taste of the fat product (after use) and the flavour of foodstuffs which have been deep- or shallow-fried in such a fat product. In the evaluation of odour impressions both the character of the odour and the intensity of the odour play a role.
From Dutch patent application NL-A-No. 6 616 686 (Unilever) it is known to prevent the development of unpleasant odours during shallow- or deep-frying by incorporating 25 to 1000 parts per million of essential oils in fat products. The non-prior published European patent application EP-A-No. 86 200 102.1 (Unilever) reports, moreover, that the development of unpleasant odours can be prevented by incorporating 0.5-50 mg linalool and/or linalyl acetate per kg product in fat products. A problem with the prevention of the development of undesired odours during for instance deep- or shallow-frying, by using products such as described above, is that, after deep-frying or shallow-frying a few times, the effect of the masking components has strongly diminished, whereafter unpleasant odours again become perceptible during deep- and shallow-frying.
U.S. patent specification U.S. Pat. No. 2,634,213 (Procter & Gamble) reports that oxidative degradation and discoloration are prevented by the addition of 0.03-0.5 ppm methyl silicones to fat products.
U.S. Pat. No. 2,998,319 (E. F. Drew) discloses the use of 1-25 ppm silicones in optionally hydrogenated vegetable oils in order to raise the decomposition temperature (smoke point).